Bottom Line:
Polystyrenesulfonate-catalyzed simple synthesis of substituted pyrroles following Paal-Knorr reaction has been accomplished with an excellent yield in aqueous solution.This method also produces pyrroles with multicyclic polyaromatic amines.The present procedure for the synthesis of N-polyaromatic substituted pyrroles will find application in the synthesis of potent biologically active molecules.

Affiliation: Department of Chemistry, The University of Texas-Pan American, 1201 West University Drive, Edinburg, TX 78539, USA. banik@utpa.edu.

ABSTRACT

Background: The classical Paal-Knorr reaction is one of the simplest and most economical methods for the synthesis of biologically important and pharmacologically useful pyrrole derivatives.

Results: Polystyrenesulfonate-catalyzed simple synthesis of substituted pyrroles following Paal-Knorr reaction has been accomplished with an excellent yield in aqueous solution. This method also produces pyrroles with multicyclic polyaromatic amines.

Conclusions: The present procedure for the synthesis of N-polyaromatic substituted pyrroles will find application in the synthesis of potent biologically active molecules.

Mentions:
Pyrroles have demonstrated important different biological activities in several areas [1]. On this basis, diverse methods for the synthesis of substituted pyrroles are known [2]. For example, Conjugate addition reaction has been developed for the preparation of pyrroles [3]. Pyrroles can also be prepared from transition metals [4], reductive coupling reaction [5], aza-Wittig reaction [6], and other multi-step reactions [7]. However, Paal-Knorr reaction is the most reliable methods for the synthesis of pyrroles [8]. Clay-induced [9] reaction and microwave irradiation method [10] have been used for the synthesis of pyrroles. Several synthetic procedures from our laboratory have also been reported [11-16]. In this article, we report simple synthesis of substituted pyrroles using an aqueous solution of polystyrenesulfonate in ethanol. Unlike many methods, synthesis of pyrroles in aqueous solution is new and challenging (Figure 1).

Mentions:
Pyrroles have demonstrated important different biological activities in several areas [1]. On this basis, diverse methods for the synthesis of substituted pyrroles are known [2]. For example, Conjugate addition reaction has been developed for the preparation of pyrroles [3]. Pyrroles can also be prepared from transition metals [4], reductive coupling reaction [5], aza-Wittig reaction [6], and other multi-step reactions [7]. However, Paal-Knorr reaction is the most reliable methods for the synthesis of pyrroles [8]. Clay-induced [9] reaction and microwave irradiation method [10] have been used for the synthesis of pyrroles. Several synthetic procedures from our laboratory have also been reported [11-16]. In this article, we report simple synthesis of substituted pyrroles using an aqueous solution of polystyrenesulfonate in ethanol. Unlike many methods, synthesis of pyrroles in aqueous solution is new and challenging (Figure 1).

Bottom Line:
Polystyrenesulfonate-catalyzed simple synthesis of substituted pyrroles following Paal-Knorr reaction has been accomplished with an excellent yield in aqueous solution.This method also produces pyrroles with multicyclic polyaromatic amines.The present procedure for the synthesis of N-polyaromatic substituted pyrroles will find application in the synthesis of potent biologically active molecules.

Affiliation:
Department of Chemistry, The University of Texas-Pan American, 1201 West University Drive, Edinburg, TX 78539, USA. banik@utpa.edu.

ABSTRACT

Background: The classical Paal-Knorr reaction is one of the simplest and most economical methods for the synthesis of biologically important and pharmacologically useful pyrrole derivatives.

Results: Polystyrenesulfonate-catalyzed simple synthesis of substituted pyrroles following Paal-Knorr reaction has been accomplished with an excellent yield in aqueous solution. This method also produces pyrroles with multicyclic polyaromatic amines.

Conclusions: The present procedure for the synthesis of N-polyaromatic substituted pyrroles will find application in the synthesis of potent biologically active molecules.